Most weight-loss supplements are ineffective

The adverts make weight loss sound so easy: Just pop some pills or mix a powder in your drink, and the excess fat melts away. That rarely impresses people who have previously tried to lose weight. They know it's never that easy.
Do any slimming supplements actually help? So-called formula products - powders mixed with milk or water that are meant to replace one or more meals daily - probably make up the largest segment of the market for weight-loss supplements.
"Many people get quickly fed up with these liquid diets, though," said Silke Schwartau, a German nutrition expert, pointing out they badly miss the enjoyment of a real meal. "And the advertising claims are exaggerated."
One problem with meal-replacement powders and shakes is that the dieter automatically tends to eat more at other meals or snacks between meals, largely nullifying the effect of the drinks.
For people who are extremely overweight, however, they could be helpful at the start of a weight-loss programme, Schwartau said.
Lars Selig, head nutritional therapist at Leipzig University Hospital, agreed. He said the drinks had the virtue of giving dieters an exactly dosed amount of calories, and for the most part also contained all essential vitamins. He, too, said liquid diets worked only when done properly.
"They're effective when they're under medical supervision and you don't eat anything - just consume three to five drinks daily, depending on the type, for seven to 10 days," Selig explained.
After that, the dieter eats one normal meal daily before gradually increasing the number. Selig said this approach was particularly helpful for people who want to - or have to - lose a lot of weight and have stopped making progress following initial successes.
"They work for a little while - after all, you're totally changing your diet," Andreas Fritsche of Tuebingen University Hospital said of the weight-loss supplements. "But then you've got to make fundamental adjustments to your food intake.
"Actually, all diets based on deprivation or restrictions are objectionable or even dangerous," Dr Fritsche added, noting that suddenly slashing calories puts the body into a state of emergency.
"The alarm bells go off, as it were. Stress hormones are released."
And with every highly restrictive diet, the body's energy metabolism drops, because it is trying with all its might to hold on to energy stores. The body adapts, and slimming down becomes twice as hard.